Combination latch bolt and friction latch



y 14, 1963 E. L SCHLAGE 3,089,720

COMBINATION LATCH BOLT AND FRICTION LATCH Filed Feb. 21, 1961 INVENTOR.

ERNEST L. SCHLAGE United States Patent 3,089,720 COHNATEGN LATCH BOLTAND FRICTIGN LATCH Ernest L. Schlage, Burlingame, Calif assignor toSchlage Lock Company, a corporation Filed Feb. 21, 1961, Ser. No. 90,7512 Claims. (Cl. 292-469) This invention relates to latch units such asare used with knob actuated door locks or latch sets, and especially toa latch bolt which is retracted by the lock a predetermined distance inthe usual manner and then functions as a friction latch or bullet catchto complete retraction.

The object of the present invention is to provide a spring projectedlatch bolt which will be retracted by a look a predetermined distance inthe usual manner and will then yield under the camming influence of astrike plate in the manner of a friction latch to complete retraction asthe door is opened.

The invention is shown by way of illustration in the accompanyingdrawings in which,

FIG. 1 is a horizontal View of the latch unit and a cooperating strikeplate, said view being partially in section.

FIG. 2 is a vertical section of the latch unit and a portion of the lockwith its retracting mechanism, and

FIG. 3 is a view similar to FIG. 1 showing the latch bolt retracted amajor portion of its stroke.

Referring to the drawings in detail, A indicates the housing of thelatch unit, 2 the latch bolt, 3 the faceplate, 4 the retractor bar, 5the spring by which the latch bolt is normally propelled to theprojected position and 6 the strike plate into which the latch boltenters when pro jected.

The spacing between the faceplate of the latch unit and the strike platewhich is mounted in the frame of the door opening is ordinarily not morethan one-sixteenth to oneeighth of an inch when the door is properlyhung or installed; but due to poor workmanship, shrinking of the door,warping of the door frame or settling of the building, the spacing mayeven exceed three-eighths of an inch, and as the average latch bolt hasa projection of only three-enghths of an inch when fully projected, thelatch bolt would be completely ineffective since it is out of engagementwith the strike plate; moreover the door would swing open in response tothe slightest draft. The latch bolt which is the subject of thisapplication is provided with a projection of half an inch but it isactuated by a standard form of retracting mechanism used with latchbolts having a three-eighths projection, in other words, the retractingmechanism is only capable of retracting the half inch projection latchbolt three-eighths of an inch, hence, other means must be provided forretracting the latch bolt the remaining portion of its projection whichis one-eighth of an inch. This is accomplished in the present instanceby forming a cam surface 7 on the strike plate.

Operation of the latch bolt mechanism will be as follows: With the latchunit and its actuating mechanism installed in a door and the strikeplate installed in the frame of the door, the door may be opened in theusual manner by grasping the knob or key and rotating it. Rotation ofthe knob or key actuates the retracting mechanism and as this is capableof retracting the latch bolt only three-eighths of an inch, the latchbolt will assume the position shown in FIG. 3. In this position theouter end 8 of the latch bolt is in contact with the cam face 7 of thestrike plate 6, thus by merely pulling on the knob, the latch bolt iscammed inwardly in the manner of a friction latch or bullet catch duringthe opening of the door.

Inasmuch as the retracting means 4 has a movement of only three-eighthsof an inch and the bolt 2 has a movement of half an inch, the connectionbetween the bolt and retractor means must be yieldable. One method ofaccomplishing this is clearly shown in FIG. 2 where 9 represents a pinfastened to the bolt and engageable in a slot Ill formed in the bar 4. Apair of shoulders 11 are formed on the bar and a pair of springs 12 areinterposed between the shoulders and the bolt, thus when the cammingaction takes place, the springs yield thereby permitting independentmovement of the latch bolt with relation to the retracting means.

It is common practice to provide a lock with what is known to the tradeas the hold-back feature, i.e., a mechanism by which a three-eighthsprojection latch bolt may be held in fully retracted position. If thehalf inch projection latch bolt and its associated strike plate aresubstituted for the three-eighths projection latch bolt, then one-eighthof the bolts tip will project and function as a friction latch. In otherwords a lock may be adjusted to function either as a friction catch oras a latch lock and friction latch combination at will.

While the latch bolt projections have been described as three-eighthsand one-half of an inch, it should be understood that these are merelyexemplary dimensions and that other lengths may obviously be employed.

While the latch unit described and shown in this application is of thetype known to the trade as a spring latch it should be understood thatthe principles described herein apply With equal validity to deadlockinglatches.

Having thus described my invention, what I desire to claim and secure byLetters Patent is,

1. In a door lock, said lock having a retractor, said retractor having afixed stroke, and a latch bolt, said latch bolt having a longer stroke,a link connecting the latch bolt with the retractor, a strike plate toreceive the latch bolt, said retractor when fully retracted retractingthe latch bolt substantially three-quarters of its stroke with relationto the strike plate, a yielding connecion between the latch bolt and theretractor permitting movement of the latch bolt beyond that caused bythe retractor, said yielding movemen permitting full retraction of thelatch bolt when a push or pull is applied to the door.

2. In a door lock, said lock having a retractor, said retractor having afixed stroke, and a latch bolt, said latch bolt having a longer stroke,a link connecting the latch bolt with the retractor, a strike plate toreceive the latch bolt, said retractor when fully retracted retractingthe latch bolt substantially three-quarters of its stroke with relationto the strike plate, a yielding connection between the latch bolt andthe retractor permitting movement of the latch bolt beyond that causedby the retractor, a cam surface on the strike plate engageable with thelatch bolt to complete retraction of the latch bolt when a push or pullis applied to the door.

References Cited in the file of this patent UNITED STATES PATENTS1,378,054 White May 17, 1921 1,486,595 Marcum Mar. 11, 1924 1,553,531Hoffman Sept. 15, 1925 2,479,174 Lickteig Aug. 16, 1949 FOREIGN PATENTS419,076 Great Britain Nov. 6, 1934 450,562 Great Britain July 21, 1936475,353 Great Britain Nov. 15, 1937

1. IN A DOOR LOCK, SAID LOCK HAVING A RETRACTOR, SAID RETRACTOR HAVING AFIXED STROKE, AND A LATCH BOLT, SAID LATCH BOLT HAVING A LONGER STROKE,A LINK CONNECTING THE LATCH BOLT WITH THE RETRACTOR, A STRIKE PLATE TORECEIVE THE LATCH BOLT, SAID RETRACTOR WHEN FULLY RETRACTED RETRACTINGTHE LATCH BOLT SUBSTANTIALLY THREE-QUARTERS OF ITS STROKE WITH RELATIONTO THE STRIKE PLATE, A YIELDING CONNECTION BETWEEN THE LATCH BOLT ANDTHE RETRACTOR PERMITTING MOVEMENT OF THE LATCH BOLT BEYOND THAT CAUSEDBY THE RETRACTOR, SAID YIELDING MOVEMENT PERMITTING FULL RETRACTION OFTHE LATCH BOLT WHEN A PUSH OR PULL IS APPLIED TO THE DOOR.